Field of the Invention
The present invention relates to an electrostrictive element and a manufacturing method therefor.
Description of the Related Art
It is known that, when electrodes are connected with both front and back surfaces of a dielectric film composed of an elastomer and voltage is applied, the dielectric film is subjected to compressive force by the Maxwell stress (piezoelectric inverse effect) from the interfacial polarization due to electrostatic force, contracts in the thickness direction and expands in the lateral direction (the direction orthogonal to the thickness direction). In recent years, there has been considered an electrostrictive element that comprises a dielectric film and electrodes and that is driven by this principle.
As such an electrostrictive element, there has been proposed a dielectric-based drive device comprising a dielectric film that is composed of an elastomer, film electrodes that are formed inside the peripheral edges of both front and back surfaces of the dielectric film and that can expand and contract so as to follow the expansion and contraction of the dielectric film, and current collectors that are connected with the peripheral edges of the film electrodes (see Japanese Patent Laid-Open No. 2003-174205, for example).
In the electrostrictive element, when a positive or negative voltage is applied to each of the film electrodes through the current collectors, the dielectric film contracts in the thickness direction and expands in the lateral direction. Thereafter, by the stop of the application, the expanded dielectric film is restored to a nearly original shape.
The film electrode is demanded to have not only a good conductivity but also a good elasticity, in order to follow the behavior of the dielectric film for the expansion without obstructing the expansion of the dielectric film.